About this Abstract |
Meeting |
Superalloys 2021
|
Symposium
|
Superalloys 2021
|
Presentation Title |
Understanding the Effects of Alloy Chemistry and Microstructure on the Stress Relaxation Behavior of Ni-base Superalloys |
Author(s) |
Linhan Li, Joshua McCarley, Eugene Y Sun, Sammy Tin |
On-Site Speaker (Planned) |
Linhan Li |
Abstract Scope |
The stress relaxation behavior of two experimental and one commercial powder processed Ni-base were assessed using a servo-hydraulic frame under strain control at 700 ˚C. In addition to quantifying the effect of composition on the stress relaxation behavior, the effect of microstructure and initial strain were also evaluated. The magnitude and rate of stress reduction for the various samples was measured during testing and an apparent activation model was used to normalize the magnitude of the stress drop with the initial stress. Stress relaxation tests with an initial strain of 0.6 % exhibited characteristic behaviors that could be correlated to alloy chemistry and microstructure. The extent of stress relaxation in highly alloyed RRHT5P samples possessing high volume fractions and a high number density of intragranular ã′ precipitates was limited. Although P additions were not observed to exert any significant effect, processing of these alloys with lower cooling rates from solution to coarsen the ã′ precipitates was shown to effectively increase the degree of stress relaxation. Reducing the degree of alloying and maintaining a lower overall fraction of ã′ precipitates effectively confers a higher degree of stress relaxation at 700 ˚C. Stress relaxation testing and the application of an apparent activation volume model may be effectively used for characterizing the notch sensitivity and crack growth behavior of high temperature structural materials. |
Proceedings Inclusion? |
Undecided |